I recall seeing something back in my CT days regarding "super-refined fuel" I don't remember where it was, I've gone looking for it.
But, recently they have discovered that metallic hydrogen can be manufactured, and might be stable at room temperatures.
What do you think about higher TL fuel processing compressing the refined hydrogen into metallic hydrogen for reduced fuel tonnage requirements.
A little bit of further research seems to indicate that a lithium-hydrogen alloy might be simpler to create, although less than half as dense, and could be introduced a TL earlier.
This would be the other side of the Metal Hydride Storage coin. Denser storage, longer legs. I know that lots of other people have come up with various approaches to home-brew longer legs.
The Fuel processor and feed systems for the power-plant would need to be modified, to accommodate the denser metallic hydrogen. The hydrogen, or alloy, would likely be stored as a fine "sand", perhaps being pumped around magnetically.

Claims of metallic hydrogen being made were announced Jan 26 2017. However, a month later the equipment broke and the samples were "lost" (which is like the science world's excuse of "my dog ate my homework, but I did it!"). Since then there's been a lot of scrutiny if metallic hydrogen had been truly made. In the months since then, it's been pointed out that the sample did not display or was not tested for a lot of the qualities that metallic hydrogen is supposed to have. It seems at this point that these claims have been discredited without proof.

There's been some tentative claims since then, but these aren't the brash announcements of last year.

It's okay to continue on with using metallic hydrogen in games (this is sci-fi after all, and we're using fusion in Traveller despite the fact nobody's actually managed to create a sustaining, controlled fusion cycle artificially yet and while there's optimism it's "only a matter of time" you never know), but in our real world metallic hydrogen still hasn't been accepted to exist; it's still something that is postulated.

Claims of metallic hydrogen being made were announced Jan 26 2017. However, a month later the equipment broke and the samples were "lost" (which is like the science world's excuse of "my dog ate my homework, but I did it!"). Since then there's been a lot of scrutiny if metallic hydrogen had been truly made. In the months since then, it's been pointed out that the sample did not display or was not tested for a lot of the qualities that metallic hydrogen is supposed to have. It seems at this point that these claims have been discredited without proof.

There's been some tentative claims since then, but these aren't the brash announcements of last year.

It's okay to continue on with using metallic hydrogen in games (this is sci-fi after all, and we're using fusion in Traveller despite the fact nobody's actually managed to create a sustaining, controlled fusion cycle artificially yet and while there's optimism it's "only a matter of time" you never know), but in our real world metallic hydrogen still hasn't been accepted to exist; it's still something that is postulated.

You're right, these guys could be total knobs. I just wasn't aware that the math indicates that metallic hydrogen might be stable at room temperatures. It opens up an avenue for questions.

I'm just trying another approach to reduce the fuel requirement of 10% dtons/jump level. Rather than questioning the requirement for a given mass of Hydrogen, I've had a new possibility come across my scope, and was looking to discuss it. It seems like an interesting approach at high TL. Might be a secret, would certainly be commercially viable, I'm just a bit tired of there being few significant differences between TL12 and TL15 ships. There are some small differences, but not as much as it seems there should be.

Metallic hydrogen is produced cheaply using the energy generated by a cold fusion reactor. During this process dark matter is concentrated to increase the pseudo-density of the hydrogen until it undergoes a phase change to metallicity and emits dark energy in the process.

No real physics was harmed during the writing of that technobabble, handwavium paragraph

Metallic hydrogen is produced cheaply using the energy generated by a cold fusion reactor. During this process dark matter is concentrated to increase the pseudo-density of the hydrogen until it undergoes a phase change to metallicity and emits dark energy in the process.

No real physics was harmed, you're right.

However, for me, it brings up something that bugs me even more - implications not being explored.

If cold fusion exists and its powerful enough to used to make metallic hydrogen (and producing "dark energy")

I would expect the superconductivity and changes in magnetic properties some researchers are theorizing to have an impact on power plant design and fuel storage. Unless we assume it transitions back to gas before going into the fusion chamber.

There is no hydrogen filled jump bubble. The writers of T4 misunderstood what was written in DGP's MR Starship Operators Manual and Mongoose have compounded this bit of fanon.

A collector powered jump drive requires no hydrogen, an antimatter power plant only requires matter/antimatter - could be hydrogen/antihydrogen, but there is no hydrogen jump bubble.

T5 clarifies this - no hydrogen filled jump bubble.

Great! the hydrogen filled bubble always bothered me. It seemed like a bit of hand-wavery to justify the 10% rule regardless of TL.

So, if a hydrogen filled bubble isn't required for canon, then the metallic hydrogen shouldn't be a problem, you feed the metallic powder into your power-plant the same way you do liquid hydrogen and when it heats up it breaks down you use it for fuel. You may have a pre-heating chamber to convert it back from metallic to gaseous, or all the way to plasma prior to feeding the power plant.

Based on the technical articles, metallic hydrogen releases even more energy when used as fuel in a chemical rocket, having a greater specific impulse, does that translate into even more energy, or greater efficiency in a fusion power-plant, or is the difference so small as to be inconsequential?

The current edition that defines the OTU is T5, the Mongoose Third Imperium is at best an ATU with close similarities.

I really like what Mongoose have done with Pirates of Drinax, and the new setting introduced in the Starter set, but everytime Mongoose publishes something that clashes with T5 it goes right to the ATU folder.